/Engine/Source/Runtime/Core/Public/Misc/ExpressionParserTypes.h
Return a string token for the next character in the stream (or accumulating into the specified existing token)
[TOptional](API\Runtime\Core\IO\TOptional)< [FStringToken](API\Runtime\Core\Misc\FStringToken) > ParseSymbol ( [FStringToken](API\Runtime\Core\Misc\FStringToken) * Accumulate ) const